Other choices of CMSs are Joomla and Wordpress... Joomla is pretty similar to Drupal, but less professional, less flexible and robust than the latter. In the market there are tens of CMSs but we don't recommend to choose any of these as the community of developers are reduced and that means the world to a CMS.
Drupal should be your first choice, not because we say so, but because we've tried the three big ones, and they are synonym of frustration
Drupal should be your first choice, not because we say so, but because we've tried the three big ones, and they are synonym of frustration... things are too simple, too narrow and any custom development needs programming skills and the code you deal with is not very structured and professional.
Drupal is powerful, scalable, flexible and future proof. A Drupal website can get converted into an E-commerce easily, can become a social network itself, a blog or cover ANY project you could have in mind.
There is no other web system like Drupal... none.